<template>
  <div class="slider"ref="slider" >
    <div class="slider-group" ref="sliderGroup">
      <slot></slot>
    </div>
    <div class="dots">
      <span class="dot" v-for="(item,index) in dots" :class="{active:currentPageIndex===index}"></span>
    </div>
  </div>
</template>

<script type="text/ecmascript-6">
  import {addClass} from 'common/js/dom'
  import BScroll from 'better-scroll'

  export default {
    name: 'slider',
    props: {
      loop: {
        type: Boolean,
        default: true
      },
      autoPlay: {
        type: Boolean,
        default: true
      },
      interval: {
        type: Number,
        default: 1000
      }
    },
    data() {
      return {
        dots: [],
        currentPageIndex: 0
      }
    },
    mounted() {
      setTimeout(() => {
        this._setSliderWidth()
        this._initDots()
        this._initSlider()
        if (this.autoPlay) {
          this._play()
        }
      }, 20)
      window.addEventListener('resize',()=>{
        this._setSliderWidth(true)
        this.slider.refresh();
      })
     },
    methods: {
      _setSliderWidth(isResize) {
          let children = this.$refs.sliderGroup.children;
          let sliderWidth=this.$refs.slider.clientWidth;
          let width = 0;
          for(let i=0;i<children.length;i++){
            let child = children[i];
            addClass(child,'slider-item');
            child.style.width=sliderWidth+'px';
            width+=sliderWidth;
          }
          if(this.loop && !isResize){
            width += 2*sliderWidth;
          }
        this.$refs.sliderGroup.style.width=width+'px';
      },
      _initSlider() {
        this.slider = new BScroll(this.$refs.slider, {
          scrollX: true,
          scrollY: false,
          momentum: false,
          snap: {
            loop: this.loop,
            threshold: 0.3,
            speed: 400
          }
        })
        this.slider.on("scrollEnd",()=>{
          let pageIndex = this.slider.getCurrentPage().pageX;
          this.currentPageIndex=pageIndex;
          if(this.autoPlay){
            this._play();
          }
        })
      },
     _initDots() {
            this.dots=new Array(this.$refs.sliderGroup.children.length)
      },
      _play() {
        clearTimeout(this.timer)
        this.timer=setTimeout(()=>{
          this.slider.next();
//          this.slider.goToPage(page,0,400)
        },this.interval)

      }
    },
    destroyed(){
        clearTimeout(this.timer)
    }
  }
</script>

<style scoped lang="scss" rel="stylesheet/stylus">
  @import "~common/scss/variable";

  .slider {
    min-height: 1px;
    .slider-group {
      position: relative;
      overflow: hidden;
      white-space: nowrap;
      .slider-item {
        float: left;
        box-sizing: border-box;
        overflow: hidden;
        text-align: center;
        a {
          display: block;
          width: 100%;
          overflow: hidden;
          text-decoration: none;
          img {
            display: block;
            width: 100%;
          }
        }
      }
    }
    .dots {
      position: absolute;
      right: 0;
      left: 0;
      bottom: 12px;
      transform: translateZ(1px);
      text-align: center;
      font-size: 0;
      .dot {
        display: inline-block;
        margin: 0 4px;
        width: 8px;
        height: 8px;
        border-radius: 50%;
        background: $color-text-l;
        &.active {
          width: 20px;
          border-radius: 5px;
          background: $color-text-ll;
        }
      }
    }

  }


</style>
